Apparatus and method for fluidizing fire-extinguishing dry chemical



p 24, 1956 M. R. BAUMAN ET AL APPARATUS AND METHOD FOR FLUIDIZING FIRE-EXTINGUISHING DRY CHEMICAL Filed Dec.

UnitedStates Patent APPARATUS AND METHOD FOR FLUIDIZING FIRE-EXTINGUISHING DRY CHEMICAL Merritt R. Batnnan, Marinette, Wis., and Alden W. Allen,

Menominee, Mich, assignors to Ansul (Shemical Company, Marinette, Wis., a corporation of Wisconsin Application December 23, 1952, Serial No. 327,592

4 Claims. (Cl. 169-11 This invention relates to dry chemical fire-extinguishing apparatus and method for fluidizing or aerating powdered dry chemical. More specifically, the invention relates to a storage container for powdered fire-extinguishing dry chemical provided with a gas inlet tube having a construction for rapidly fiuidizing and pressurizing the stored dry chemical so that it may be efiectively ejected in a stream from the storage container for fire-extinguishing purposes while the ratio of dry chemical to gas in the stream remains substantially unaltered.

Dry chemical fire extinguishers usually comprise a storage container for storing powdered dry chemical which is a composition containing essentially sodium bicarbonate, as disclosed in Patent 1,793,420, February 17, 1931. Since the powdered sodium bicarbonate absorbs moisture which will cause it to cake, it is necessary to store the dry chemical in a container which is sealed against entry of moisture therein. The storage container is connected to a suitable source of gas pressure, such as cylinders of compressed carbon dioxide, nitrogen, or air which when released within the storage chamber will fluidize or aerate the dry chemical and expel the fluidized powdered dry chemical under pressure through an outlet provided in the storage chamber which may be connected to a pipe or hose for conveying the stream of dry chemical to the location where a fire is to be extinguished.

When dry chemical type fire extinguishers were first developed, the need for aerating the dry chemical to fluidize it to promote free flowing was discovered. This need was fulfilled by introducing the expellant gas into the dry chemical container at or near the bottom of the container.

With the development of larger equipment, particularly equipment using dry chemical discharge lines of substantial length, it became necessary to introduce additional gas during the period when the extinguisher was being discharged. This and the above-mentioned fluidizing were accomplished by using a pressure regulator and introducing the gas through a gas tube with its outlet located at or near the bottom of the dry chemical container. This arrangement, now in common use, has several disadvantages. First, the pressurizing time is limited by the capacity of the regulator. equipment rapid actuation of the device is essential. Regulators having adequate capacity to feed gas into the dry chemical container during discharge of the extinguisher do not provide rapid pressurization of the extinguisher.

Second, in order to fluidize the dry chemical, the pressurizing gas must be introduced at or near the bottom of the dry chemical container. The dry chemical outlet from the container must also be located at or near the bottom of the container. During discharge of the extinguisher, the gas introduced through the gas tube to keep the pres sure in the container at a suitable operating level alters the gas-to-dry chemical ratio of the discharging stream initially established during pressurization. This results In a piece of fire fighting 2,742,970 Patented 24,- 1956 2 in a high gas-to-dry chemical ratio, a more gassystream, and-a lower flew rate or dry chemical. r I

Compromise gas tubes havebeen worked out to strike a compromise on the two cited points. The present invention overcomes the cited problems andhas other advantages that will be evident in further examination of the description of this device.

-Further' details and advantages of the invention will be apparent from the followingspecification and appended drawing, wherein l The figure is a diagrammatic arrangement, partly in section, illustrating the features of our invention.

Referring to the drawing, the" device comprises essentially a dry chemical chamber 10 equippedwith twngas tubes. One tube 26 is located at or near the bottom of the container 10 and is directly connected to a gas pressure source, such as gas cylinder 15, controlled by valve 14, without the usual intervening regulators. The gas pressure source is of such capacity that it will, when totally discharged; bring the extinguisher to a near its normal operating pressure. Tube 26 is connected to a nozzle positioned adjacent the bottom of. the chamber 10. The nozzle may have a single or a plurality of openings 11. The other gas tube 17 is located at or near the top of the chamber 10 and is connected by a coupling 2 to a regulator 3 (or regulators) and a gas pressure source 5 controlled by valve 4 that may comprise one or more gas cylinders. Tube 17 is connected to a nozzle 7 positioned in the upper zone 6 of the chamber 10.. The nozzle 7 may be provided with a single or a plurality of openings 8.

Actuation of the cylinder valve 14 on the gas cylinder 15 directly connected with the lower gas tube 16 causes the gas in the cylinder to discharge directly into the dry chemical chamber 10. This causes very rapid pressurization of the chamber 10, aerates or iiuidizes the dry chemical 18 therein, and brings the extinguisher approximately to its normal operating pressure. p

Immediately afterward, opening of the cylinder valve 4 on the cylinder 5 attached to the upper gas tube 17 places said cylinder in communication with the dry chemical chamber 10 through the pressure regulator 3. When the extinguisher is then operated and dry chemical is expelled from the container through outlet 16, controlled by valve 13, additional gas will go through the pressure regulator and enter the container at or near the top of the container, thus keeping the pressure in the extinguisher at the operating pressure predetermined by the setting of the pressure regulator. Gas so introduced will not substantially disrupt the gas-to-dry chemical ratio and the resultant dry chemical fire-fighting stream will be dense and have a relatively higher flow rate of greater fire fighting capacity.

We wish it to be understood that we do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

We claim:

1. An apparatus for supplying gas-fluidized dry chemical at a substantially constant ratio of gas to dry chemical which comprises a chamber for storing dry chemical therein, an outlet in said chamber, a source of fluidizing gas pressure connected to the bottom of said chamber, and a second source of gas pressure connected to the upper portion of said chamber to maintain a substantially constant pressure in said chamber while the fluidized dry chemical is being discharged from said chamber at a substantially constant ratio of gas to dry chemical.

2. An apparatus for supplying gas-fluidized dry chem ical at a substantially constant ratio of gas to dry chemical which comprises a chamber for storing dry chemical therein, an outlet in said chamber, a nozzle adjacent the bottom of said chamber, a source of fiuidizing gas connected to said nozzle, and a second source of gas pressure connected .to the ,upper portion of said chamber to maihtain a substantially constant pressure in said chamber I While the fluidized dry chemical is being discharged from said chamber at a substantially constant ratio of gas to dry chemical. .l v I H I 3. An'apparatus for supplying gas-fluidized dry chemical at a substantially constant ratio of gas to dry chemical which comprises a chamber for storing dry chemical therein, an outlet in said chamber, a source of gas pressure connected to the bottom of said chamber for fiuidizing the dry chemical in said chamber and also connected to the upper portion of said chamber to maintain a substantially constant pressure in said chamber while the fluidized dry chemical is being discharged from said chamber at a substantially constant ratio of gas to dry chemical.

4; An apparatus for supplying gas-fluidized dry chemical at a substantially constant ratio of gas to dry chemical which comprises a chamber for storing dry chemical "therein, an outlet in said 4. chamber for -discharging gas fluidized dry chemical, a source of gas pressure to pressurize the tank to approximate operating pressure connected to discharge into thelower portion of said chamber to fiuidize said dry chemical when the chamber is pressurized and a source of gas at regulated pressure connected to the upper portion of said chamber to maintain substantially constant operating pressure while dry chemical is being discharged.

References Cited in the file of this patent UNITED STATES PATENTS 1,169,646 Jaretzki Jan. 25, 1916 2,473,349 Snowden June 14,.1949 2,642,944 Allen June 23, 1953 2,681,115 Guise June 15, 1954 

1. AN APPARATUS FOR SUPPLYING GAS-FLUIDIZED DRY CHEMICAL AT A SUBSTANTIALLY CONSTANT RATIO OF GAS TO DRY CHEMICAL WHICH COMPRISES A CHAMBER FOR STORING DRY CHEMICAL THEREIN, AN OUTLET IN SAID CHAMBER, A SOURCE OF FLUIDIZING GAS PRESSURE CONNECTED TO THE BOTTOM OF SAID CHAMBER, AND A SECOND SOURCE OF GAS PRESSURE CONNECTED TO THE UPPER PORTION OF SAID CHAMBER TO MAINTAIN A SUBSTANTIALLY CONSTANT PRESSURE IN SAID CHAMBER WHILE THE FLUIDIZED DRY CHEMICAL IS BEING DISCHARGED FROM SAID CHAMBER AT A SUBSTANTIALLY CONSTANT RATIO OF GAS TO DRY CHEMICAL. 